Method of making collapsible tubes



E. STATHER-DUNN ETAL 2,416,962

METHOD OF MAKING COLLAPSIBLE TUBES Filed March 31, 1945 Jizvenfars EUSTACE STATHER DUNN FRANK MARSHALL MENHENEOTT 3y *Z'7zez'r' afio-ne ys Patented Mar. 4, 1947 METHGD or MAKING COLLAPSIBLE TUBES Eustace Stather-Dunn and Frank Marshall Menheneott, County of London, England, assignors to Betts & Company Limited, London County, England, a company of Great Britain Application March 31, 1943, Serial No. 481,334 In Great Britain May 26, 1942 '7 Claims.

This invention relates to a method of making collapsible tubes which have a flexible tubular body portion or barrel which is not made of metal.

It has already been proposed to make a collapsible tube of which the barrel is a non-metallic plastic material but it is not easy to attach the barrel to the shoulder so as to effect a satisfactory seal between them in a manner which is both simple to manufacture and eficient in use. As far as is known no satisfactory tube of such character has been marketed, at least on any large scale. In prior arrangements the end of the barrel has been sealed either to the under part or to the edge of the shoulder either by a clamping device or simply by cementing, but in such a way that the strength of the tube is determined by the strength of the joint. There are other prior arrangements in which the barrel and the shoulder and nozzle of the tube are entirely of the same material, the shoulder or the shoulder and nozzle being merely continuations of the barrel and made of the same material, but their flexible nature renders them unsatisfactory. Such tubes have obvious weaknesses.

According to the present invention a seamless collapsible tube is made by temporarily attaching a preformed shoulder to one end of a mandrel and a non-metallic plastic tubular body portion is formed thereon by applying one or more coats of a non-metallic plastic material in a fluid state over the mandrel and the outside of the preformed shoulder, the mandrel being covered prior to the coating operation with a thin film of a lubricant which is incompatible with the fluid plastic material. The non-metallic plastic material will thus form a tubular body portion one end of which passes without interruption into the form of an annular flange externally covering the preformed shoulder. The arrangement has the advantage that pressure inside the collapsible tube caused when the contents are squeezed out instead of tending to break the seal between the barrel and the preformed shoulder will in fact tend to tighten the seal.

In the accompanying drawings, Figure 1 illustrates a method of making a colla sible tube in accordance with the invention, the tube so formed being shown in Figure 2.

Referring to Figure 1, for the purpose of making the collapsible tube, use is made of a mandrel having a cylindrical portion I with a conical end 2. The top of the cone is provided with a threaded hole 3 adapted to receive a bolt 4. The cone is designed to receive a shoulder 5 which may have a nozzle 5 integral therewith, this part having been previously formed. The preformed shoulder and nozzle is placed on the conical end 2 of the mandrel, the bolt 4 having been previously removed, and the bolt 4 is then screwed into the hole 3 to clamp the shoulder and nozzle firmly to the mandrel. The mandrel is then covered with a thin film of a lubricant which is incompatible with the fluid plastic material to be used. The tubular body portion 1 of the collapsible tube is then formed by applying one or more coats of the fluid plastic material to cover the shoulder and the mandrel as shown in Figure 1. When the fluid has dried or set, the bolt 4 is removed, the mandrel is withdrawn, and the tube as shown in Figure 2 remains. The use of the thin film of lubricant on the mandrel is essential since without it the plastic material, on setting, would grip the mandrel so tightly that the mandrel could not be removed without. completely ruining the tube.

'The process of coating the fluid plastic material on the shoulder and mandrel may be carried out either by dipping the mandrel with the attached shoulder into one or more baths of fluid plastic material or by spraying fluid plastic material on to the mandrel and shoulder, or by applying one or more coats of the fluid plastic material to the mandrel and shoulder either by suitably designed and positioned rollers or by the use of suitable brushes.

Although the seal between the barrel and the shoulder produced by this method is a self-tightening one, further protection against egress from the tube of contents which may be of a particularly penetrating character may be eflected either by coating the preformed shoulder with a sealing compound or a gum or a solvent which renders the surface of the shoulder slightly glutinous before applying the fluid plastic material to the mandrel and shoulder. If the preformed shoulder be made of metal or other non-readily soluble material such as glass, the seal can be improved in the same way by so marking the outer surface of the preformed shoulder as to provide a key for the plastic coating which is then applied.

The mandrel may not necessarily be cylindrical, but is preferably slightly tapered outwards from the shoulder end (as is shown in Figure '1) so as to make it more easily withdrawn from the plastic tube after the fluid plastic material has dried or set, thereby assisting the action of the lubricant on the mandrel.

As non-metallic plastic materials for the tubular body portion may be mentioned for example: cellulose derivatives, synthetic or natural resins or gums, shellac, rubber or gelatinous compounds. It is not necessary that only one of these ma terials should be used in any one tube, but successive layers from which the tubular body portion may be built up by any of the methods above described may be of a different material; as an example a tube might be required in which the contents called for the use of a gelatinous compound on the inner surface, but the strength of the tube must be greater than that possible with a gelatinous compound, in which case a first layer might be formed from gelatinous compounds by any of the processes mentioned above and subsequent layers of other fluid plastic material.

The fluid plastic material may contain any harmless dye or pigment applied either uniformly throughout the whole of the tubular body portion or.in such a manner as to provide a combination of colours in all or any of the layers of the applied fluid plastic material.

After the collapsible tube has been filled the open end has to be closed. This may be effected by applying to a sufficient length of the open end as may be necessary a suitable adhesive so that after the end has been folded and placed in the jaws of a pincer machine the folded portion is cemented together and completely seals the tube against egress of its contents without the use of any additional reinforcements. Instead of a separate adhesive the open end of the tube can be made sufficiently adherent by applying a solvent for the plastic material, the solvent being applied no longer than is necessary to make the surface glutinous. The adhesive or solvent can be applied by dipping, rolling, spraying or brushing. If the plastic material be made such that it will commence to melt on the .outer surface when heat is applied by the jaws of the pincer machine no special application of adhesive or solvent to the end of the tube is necessary. The tube may, of course, also be closed by any of the well known methods of affixing a separate cli Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim'is:

1. The method of making a seamless collapsible tubeconsisting of temporarily attaching a preformed shoulder and nozzle to one end of a mandrel having a hard smooth surface integral therewith by attaching mean-s extending through said nozzle, covering the mandrel surface with a thin film of a lubricant which is incompatible with a fluid plastic material to be used, and thereafter forming directly upon the coated mandrel surface and the pre-formed shoulder only at least one coat of a non-metallic plastic material in the fluid state, allowing the fluid material to solidify to a plastic state, releasing said attaching means and sliding the mandrel out of the coating tube thereby formed.

2;. The method of making a seamless collapsible tube consisting of temporarily attaching a preformed shoulder and nozzle to one end ofa mandrel having a hard smooth surface integral therewith by attaching means extending through said nozzle, covering the mandrel surface with a surface and the pre-formed shoulder only a plurality of coats of non-metallic plastic material in the fluid state, after each coating allowing the fluid material to solidify to a plastic state, releasing said attaching means and sliding the-mandrel out of the coating tube thereby formed.

3. The method of making a seamless collapsible tube consisting of temporarily attaching a preformed shoulder and nozzle to one end of a mandrel having a hard smooth surface integral therewith by attaching means extending through said nozzle, covering the mandrel surface with a thin film of a lubricant which is incompatible with afluid plastic material to be used, treating the outer surface of the preformed shoulder to enhance its compatibility with said plastic material, and thereafter forming directly upon the coated mandrel surface and the pre-formed shoulder only at least one coat of a nonnnetallic plastic material in the fluid state, allowing the fluid material to solidify to a plastic state, releasing said attaching means and sliding the mandrel out of the coating tube thereby formed.

4. The method of making a seamless collapsible tube, consisting of temporarily attaching to one end of a mandrel having a hard smooth surface integral therewith a preformed shoulder and nozzle made of non-readily soluble material having an outer surface marked to provide a key for a plastic coating by attaching means extending' through said nozzle, covering the mandrel surface with a thin film of a lubricant whichis. incom patible with a fluid plastic material to be used; and thereafter forming directly upon the coated mandrel surface and the pro-formed shoulder only at least one coat of a non-metallic plastic material in the fluid state, allowing the fluid material to solidify to a plastic state, releasing said attaching means and sliding the. mandrel out of the coating tube thereby formed. I

5. The method of making a seamless collapsible tube consisting of temporarily attaching a pre formed shoulder and nozzle to one end of amandrel having a hard smooth surface integral therewith by attaching means extending through said nozzle, covering the mandrel surface with a thin film of a lubricant incompatibie with the'fiuid plastic material to be used, forming directly upon the coated mandrel'surface and the pro-formed der and nozzleto one end of' a mandrel shaped to conform to said shoulder and having a hard smooth surface integral therewith by attaching means extending'through' said nozzle, covering the mandrel surface with a thin film of a lubricantwhich is'incompatible with a fluid plastic material to be used, and thereafter 'forming'jdirectly upon the coated mandrel surface and. the

seamless collapsible ,tube consisting of attaching a preformed shoul pre-formed shoulder only a coating of non-metallic plastic material in the fluid state, allowing the fluid material to solidify to a plastic state, releasing the attaching means, and sliding the mandrel out of the coating tube thereby formed.

7. A method of making a seamless collapsible tube consisting of attaching a pre-formed shoulder having a discharge nozzle for the tube to one end of a mandrel shaped to conform to said shoulder and having a hard smooth surface integral therewith by attaching means engaging in said discharge nozzle, covering the mandrel surface with a thin film of a lubricant which is incompatible with a fluid plastic material to be used, and thereafter forming directly upon the coated mandrel surface and the pre-formed shoulder only a coating of non-metallic plastic material in the fluid state, allowing the fluid material to solidify to a plastic state, releasing said attaching means and sliding the mandrel out of the coating tube thereby formed.

EUSTACE STATHER-DUNN. FRANK MARSHALL MENHENEOTT.

REFERENCES CITED The following references are of record in the file of this patent:

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